Semiconductor light-emitting element, manufacturing method of semiconductor light-emitting element, and semiconductor device

ABSTRACT

A semiconductor light-emitting element includes a laminated structure which has an active layer between a first conductivity-type semiconductor layer and a second conductivity-type semiconductor layer, a first semiconductor layer which includes at least the first conductivity-type semiconductor layer of the laminated structure, an insulation film which is formed on the first semiconductor layer and has an opening, and a second semiconductor layer which is formed on the insulation film and includes at least the second conductivity-type semiconductor layer of the laminated structure. The second semiconductor layer includes a first region facing the opening of the insulation film and a second region not facing the opening, and the second region has a portion with a higher impurity concentration than the first region.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional Application of patent application Ser.No. 14/633,363, filed Feb. 27, 2015, which claims the benefit ofJapanese Priority Patent Application JP 2014-046042 filed Mar. 10, 2014,the entire contents of which are incorporated herein by reference.

BACKGROUND

The present disclosure relates to a semiconductor light-emitting elementsuch as a semiconductor laser or a light-emitting diode (LED), amanufacturing method thereof, and a semiconductor device.

In the semiconductor laser, a ridge portion is formed by etching and theridge portion is interposed by an insulation film after forming asemiconductor laminated structure on a substrate, and thereby it ispossible to realize a current constriction and to obtain a low thresholdcurrent density (for example, S. Nakamura et. Al., Appl. Phys. Lett. 69(1996) 1477). In addition, since it is possible to have a difference inrefractive index inside and outside the ridge portion by selecting amaterial having a lower refractive index than the semiconductor as amaterial of the insulation film, a so-called light transverse mode iseasily controlled. However, in such a structure, since an electrode areais limited to a width of the ridge portion or less, a contact resistancewith the electrode or a semiconductor bulk resistance is caused to beincreased, and thereby a drive voltage is increased.

Therefore, in order to reduce the above resistance while performing acurrent constriction, a method of forming the ridge portion by a crystalgrowth after forming an insulation film having an opening on thesemiconductor layer is proposed (for example, Japanese Unexamined PatentApplication Publication No. 10-190142).

SUMMARY

In the semiconductor light-emitting element described above, forexample, as a light source application of an optical disk or a display,there is a demand for a higher output so as to realize a high speed ofthe optical disk or a high brightness of the display. When the higheroutput is realized, a further reduction of a drive voltage is desired.

It is desirable to provide a semiconductor light-emitting element, amanufacturing method thereof, and a semiconductor element which canreduce a drive voltage.

According to a first embodiment of the present disclosure, there isprovided a semiconductor light-emitting element, including a laminatedstructure which has an active layer between a first conductivity-typesemiconductor layer and a second conductivity-type semiconductor layer,a first semiconductor layer which includes at least the firstconductivity-type semiconductor layer of the laminated structure, aninsulation film which is formed on the first semiconductor layer and hasan opening, and a second semiconductor layer which is formed on theinsulation film and includes at least the second conductivity-typesemiconductor layer of the laminated structure. The second semiconductorlayer includes a first region facing the opening of the insulation filmand a second region not facing the opening, and the second region has aportion with a higher impurity concentration than the first region.

In the semiconductor light-emitting element of the first embodiment ofthe disclosure, the second semiconductor layer is formed on the firstsemiconductor layer through the insulation film having an opening. Inthe second semiconductor layer, the second region not facing the openingof the insulation film includes a portion which has a higher impurityconcentration than the first region facing the opening, and thereby acurrent path in the second semiconductor layer is expanded.

According to a second embodiment of the present disclosure, there isprovided a semiconductor light-emitting element, including a laminatedstructure which has an active layer between a first conductivity-typesemiconductor layer and a second conductivity-type semiconductor layer,a first semiconductor layer which includes at least the firstconductivity-type semiconductor layer of the laminated structure, aninsulation film which is formed on the first semiconductor layer and hasan opening, and a second semiconductor layer which is formed on theinsulation film and includes at least the second conductivity-typesemiconductor layer of the laminated structure. The second semiconductorlayer includes a first region facing the opening of the insulation filmand a second region not facing the opening, and the second region has asmaller electrical resistivity than the first region.

In the semiconductor light-emitting element of the second embodiment ofthe disclosure, the second semiconductor layer is formed on the firstsemiconductor layer through the insulation film having an opening. Inthe second semiconductor layer, the second region not facing the openingof the insulation film has a smaller electrical resistivity than thefirst region facing the opening, and thereby a current path in thesecond semiconductor layer is expanded.

According to a third embodiment of the present disclosure, there isprovided a semiconductor light-emitting element, including a laminatedstructure which has an active layer between a first conductivity-typesemiconductor layer and a second conductivity-type semiconductor layer,a first semiconductor layer which includes at least the firstconductivity-type semiconductor layer of the laminated structure, aninsulation film which is formed on the first semiconductor layer and hasan opening, and a second semiconductor layer which is formed on theinsulation film and includes at least the second conductivity-typesemiconductor layer of the laminated structure. The second semiconductorlayer includes a first region facing the opening of the insulation filmand a second region not facing the opening, and a path of carriers inthe second semiconductor layer is configured so as to be expanded morethan a width of the opening of the insulation film.

In the semiconductor light-emitting element of the third embodiment ofthe disclosure, the second semiconductor layer is formed on the firstsemiconductor layer through the insulation film having an opening. Thesecond semiconductor layer includes the first region facing the openingof the insulation film and the second region not facing the opening, anda carrier path is configured to be expanded more than a width of anopening of the insulation film, and thereby a current path in the secondsemiconductor layer is expanded.

According to an embodiment of the disclosure, there is provided a methodof manufacturing a semiconductor light-emitting element, includingforming a first semiconductor layer which includes at least a firstconductivity-type semiconductor layer of a laminated structure that hasan active layer between the first conductivity-type semiconductor layerand a second conductivity-type semiconductor layer, forming aninsulation film which has an opening on the first semiconductor layer,and forming a second semiconductor layer which includes at least thesecond conductivity-type semiconductor layer of the laminated structureon the insulation film. In the forming of the second semiconductorlayer, a first region facing an opening of the insulation film isformed, and a second region not facing the opening is formed byselective growth after forming the first region.

In the method of manufacturing a semiconductor light-emitting element ofthe embodiment of the disclosure, the second semiconductor layer isformed on the first semiconductor layer through the insulation filmhaving an opening. When forming the second semiconductor layer, thesecond region not facing the opening is formed by a selective growthafter the first region facing the opening of the insulation film isformed, and thereby a current path in the second semiconductor layer canbe expanded.

According to an embodiment of the disclosure, there is provided asemiconductor device, including a first semiconductor layer, aninsulation film which is formed on the first semiconductor layer and hasan opening, and a second semiconductor layer which is formed on theinsulation film, in which the second semiconductor layer includes afirst region facing the opening of the insulation film, and a secondregion not facing the opening. The second region has a portion with ahigher impurity concentration than the first region or has a smallerelectrical resistivity than the first region.

In the semiconductor device of the embodiment of the disclosure, thesecond semiconductor layer is formed on the first semiconductor layerthrough the insulation film having an opening, and the secondsemiconductor layer includes a first region facing the opening of theinsulation film and a second region not facing the opening. The secondregion of the second semiconductor layer includes a portion which has ahigher impurity concentration than the first region, or has a smallerelectrical resistivity than the first region, and thereby a current pathin the second semiconductor layer is expanded.

In the semiconductor light-emitting element of the first embodiment ofthe disclosure, the second semiconductor layer is formed on the firstsemiconductor layer through the insulation film having an opening. Thesecond region not facing the opening of the insulation film in thesecond semiconductor layer includes a portion which has a higherimpurity concentration than the first region facing the opening, andthereby it is possible to expand a current path in the secondsemiconductor layer and to reduce bulk resistance of the secondsemiconductor layer. Accordingly, it is possible to reduce a drivevoltage.

In the semiconductor light-emitting element of the second embodiment ofthe disclosure, the second semiconductor layer is formed on the firstsemiconductor layer through the insulation film having an opening. Thesecond region not facing the opening of the insulation film in thesecond semiconductor layer has a smaller electrical resistivity than thefirst region facing the opening, and thereby it is possible to expand acurrent path in the second semiconductor layer and to reduce a bulkresistance of the second semiconductor layer. Accordingly, it ispossible to reduce a drive voltage.

In the semiconductor light-emitting element of the third embodiment ofthe disclosure, the second semiconductor layer is formed on the firstsemiconductor layer through the insulation film having an opening, thesecond semiconductor layer includes the first region facing the openingof the insulation film and the second region not facing the opening, anda carrier path in the second semiconductor layer is configured so as tobe expanded more than a width of the opening of the insulation film.Accordingly, it is possible to expand a current path in the secondsemiconductor layer and to reduce a bulk resistance of the secondsemiconductor layer. Accordingly, it is possible to reduce a drivevoltage.

In the method of manufacturing a semiconductor light-emitting element ofthe embodiment of the disclosure, in the forming of the secondsemiconductor layer on the first semiconductor layer through theinsulation film having an opening, the second region not facing theopening is formed by a selective growth after the first region facingthe opening of the insulation film is formed. Accordingly, it ispossible to expand a current path in the second semiconductor layer andto reduce a bulk resistance. As a result, it is possible to realize asemiconductor light-emitting element which can reduce a drive voltage.

In the semiconductor device of the embodiment of the disclosure, thesecond semiconductor layer is formed on the first semiconductor layerthrough the insulation film having an opening, and the secondsemiconductor layer includes the first region facing the opening of theinsulation film and the second region not facing the opening. The secondregion of the second semiconductor layer includes a portion which has ahigher impurity concentration than the first region, or has a smallerelectrical resistivity than the first region, and thereby it is possibleto expand a current path in the second semiconductor layer and to reducea bulk resistance. As a result, it is possible to reduce a drivevoltage.

The above content is an example of the present disclosure. Effects ofthe disclosure are not limited to those described above. However, theeffects of the disclosure may also be other different effects, or mayfurther include other effects.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view which shows a configuration of asemiconductor light-emitting element according to an embodiment of thepresent disclosure;

FIG. 2 is a flow diagram which describes a manufacturing method of thesemiconductor light-emitting element shown in FIG. 1;

FIG. 3A is a schematic diagram which describes a formation process of asecond semiconductor layer shown in FIG. 2;

FIG. 3B is a schematic diagram which describes a process subsequent toFIG. 3A;

FIG. 3C is a schematic diagram which describes a process subsequent toFIG. 3B;

FIG. 4A is a schematic diagram which shows a configuration of a mainportion of the semiconductor light-emitting element according toComparative Example 1;

FIG. 4B is a schematic diagram which describes an operation of thesemiconductor light-emitting element shown in FIG. 4A;

FIG. 5A is a schematic diagram which shows a configuration of a mainportion of the semiconductor light-emitting element according toComparative Example 2;

FIG. 5B is a schematic diagram which describes an operation of thesemiconductor light-emitting element shown in FIG. 5A;

FIG. 6A is a schematic diagram which shows a configuration of a mainportion of the semiconductor light-emitting element according toComparative Example 3-1;

FIG. 6B is a schematic diagram which shows a configuration of a mainportion of the semiconductor light-emitting element according toComparative Example 3-2;

FIG. 7 is a schematic diagram which describes an operation of thesemiconductor light-emitting element shown in FIG. 1;

FIG. 8 is a characteristic diagram which shows a relationship betweenelement differential resistance and a current value;

FIG. 9 is a characteristic diagram which shows a relationship between acurrent density and a distance from the center of a ridge portion;

FIG. 10 is a characteristic diagram which shows a relationship (V-Icharacteristics) of a voltage and a current;

FIG. 11 is a characteristic diagram which shows a relationship between alight output (L-I characteristics) and a current;

FIG. 12A shows a current density distribution of a model shown in FIG.5A;

FIG. 12B is an enlarged diagram of a portion of FIG. 12A;

FIG. 13A shows a current density distribution of a model shown in FIG.1;

FIG. 13B is an enlarged portion of a portion of FIG. 13A;

FIG. 14 is a cross-sectional view which shows a configuration of thesemiconductor light-emitting element according to Modification Example1;

FIG. 15 is a cross-sectional view which shows a configuration of thesemiconductor light-emitting element according to Modification Example2;

FIG. 16 is a cross-sectional view which shows a configuration of thesemiconductor light-emitting element according to Modification Example3;

FIG. 17 is a cross-sectional view which shows a configuration of thesemiconductor light-emitting element according to Modification Example4;

FIG. 18 is a cross-sectional view which shows a configuration of thesemiconductor light-emitting element according to Modification Example5; and

FIG. 19 is a cross-sectional view which shows a configuration of thesemiconductor light-emitting element according to Modification Example6.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present disclosure will be described indetail with reference to drawings. A description will proceed in thefollowing order.

1. Embodiment (an example of a semiconductor light-emitting elementhaving a first region and a second region which have different impurityconcentrations in a ridge portion)

2. Modification Example 1 (an example of the semiconductorlight-emitting element having another laminated structure)

3. Modification Example 2 (an example in which a plurality of insulationfilms are formed)

4. Modification Example 3 (an example when a second region has animpurity concentration distribution)

5. Modification Example 4 (an example when a boundary between the firstregion and the second region is tapered)

6. Modification Example 5 (an example when having a third region on thefirst region)

7. Modification Example 6 (an example in which an electrode forcontrolling a current path is provided in the second region)

EMBODIMENTS

Configuration

FIG. 1 shows a configuration of a semiconductor light-emitting element(semiconductor light-emitting element 1) according to an embodiment ofthe present disclosure. The semiconductor light-emitting element 1 is aso-called edge light-emitting type which interposes a laminatedstructure having an active layer between an n-type (firstconductivity-type) semiconductor layer and a p-type (secondconductivity-type) semiconductor layer over a pair of resonator edgeswhich are not shown. FIG. 1 schematically shows a configuration of amain portion of the semiconductor light-emitting element 1, and can bedifferent from an actual dimension and an actual shape.

The semiconductor light-emitting element 1 is, for example, anitride-based semiconductor laser, and is obtained by bringing up aso-called group III-V nitride semiconductor layer on a GaN substrate(nitride semiconductor substrate). The group III-V nitride semiconductoris a gallium nitride-based compound which includes gallium (Ga) andnitrogen (N), and GaN, aluminum gallium nitride (AlGaN), aluminumgallium indium nitride (AlGaInN), or the like is exemplified as anexample. These include an n-type impurity which is made of group IV andgroup VI elements such as silicon (Si), germanium (Ge), and oxygen (O),selenium (Se), or a p-type impurity which is made of group II and groupIV elements such as magnesium (Mg), zinc (Zn), and carbon (C) whennecessary.

In the semiconductor light-emitting element 1, for example, an n-typeAlGaN cladding layer (n-type cladding layer 13), an n-type GAN opticalguide layer (n-type optical guide layer 14), and an active layer 15including an n-type GaInN layer (quantum well layer) and an n-type GaInNlayer (barrier layer) are formed on a c-plane GaN substrate (substrate12) in this order. A p-type AlGaN electron barrier layer (p-typeelectron barrier layer 16) and a p-type AlGaN cladding layer (p-typecladding layer 17) are formed on the active layer 15 in this order.Here, these n-type cladding layer 13, n-type optical guide layer 14,active layer 15, p-type electron barrier layer 16, and p-type claddinglayer 17 configure the first semiconductor layer 10, and the insulationfilm 18 is formed on the first semiconductor layer 10.

The insulation film 18 has an opening H1 extending in a predetermineddirection. A first region 19A and a second region 19B are formed on theinsulation film 18 as a second semiconductor layer 19 (ridge portion,ridge stripe). The first region 19A is formed to face the opening H1,and the second region 19B is formed not to face the opening H1 (formedin a region not facing the opening H1).

Specifically, the first region 19A is formed, for example, in a stripeshape in an extending direction of the opening H1, and the second region19B is formed next to (on a side surface of) the first region 19A (so asto interpose the first region 19A between both sides). However, thesecond region 19B may be formed to be adjacent to at least a portion ofthe side surface of the first region 19A. The second semiconductor layer19 has these first region 19A and second region 19B, and thereby acontact area between the second semiconductor layer 19 and the p-sideelectrode 21 is larger than an area of the opening H1 of the insulationfilm 18, the detail will be described later.

The first region 19A and the second region 19B are made of, for example,a p-type AlGaN; however, raw material ratios (composition ratio orimpurity concentration) are different from each other. The p-sideelectrode 21 is formed on the second semiconductor layer 19 through ap-type GaN contact layer (p-type contact layer 20). An n-side electrode11 is formed on a rear surface of the substrate 12. In FIG. 1, alaminated structure including the first semiconductor layer 10 and thesecond semiconductor layer 19 is formed so as to be interposed by then-side electrode 11 and the p-side electrode 21; however, formationplaces of the n-side electrode 11 and the p-side electrode 21 are notlimited thereto. The n-side electrode 11 may be electrically connectedto the first semiconductor layer 10 (the n-type cladding layer 13 indetail), and the p-side electrode 21 may be electrically connected tothe second semiconductor layer 19. The second semiconductor layer 19 isconfigured to have a compound semiconductor containing, for example,nitrogen (N) and at least one element of gallium (Ga), aluminum (Al),indium (In), and boron (B).

The n-type cladding layer 13 is made of, for example, n-typeAl_(0.06)Ga_(0.94)N, and is doped with, for example, silicon (Si) oroxygen (O) as an n-type impurity. A thickness of the n-type claddinglayer 13 is, for example, 2 μm. A thickness of the n-type optical guidelayer 14 is, for example, 100 nm, and the n-type optical guide layer 14is doped with, for example, silicon (Si) or oxygen (O) as an n-typeimpurity. A quantum well layer of the active layer 15 is made of, forexample, Ga_(0.92)In_(0.08)N, and a thickness thereof is, for example, 5nm. In this case, a light emission wavelength of a nitride semiconductorlaser is about 400 nm. A barrier layer of the active layer 15 is madeof, for example, Ga_(0.98)In_(0.02)N, and a thickness thereof is, forexample, 10 nm. The number of quantum well layers in the active layer 15is, for example, three, and the active layer 15 has a so-called multiplequantum well structure. The p-type electron barrier layer 16 is made of,for example, a p-type Al_(0.20)Ga_(0.80)N, and is doped with, forexample, magnesium (Mg) as a p-type impurity. A thickness of the p-typeelectron barrier layer 16 is, for example, 10 nm. The p-type claddinglayer 17 is made of, for example, Al_(0.04)Ga_(0.96)N, and is doped withmagnesium (Mg) as a p-type impurity. A thickness of the p-type claddinglayer 17 is, for example, 0.1 μm.

The insulation film 18 is made of, for example, SiO₂, and a filmthickness of the insulation film is, for example, 100 nm. In addition, awidth of an opening H1 of the insulation film 18 is, for example, 1.5μm.

The first region 19A of the second semiconductor layer 19 is made of,for example, Al_(0.04)Ga_(0.96)N, and is doped with, for example,magnesium (Mg) as a p-type impurity. A thickness of the first region 19Ais, for example, 0.5 μm. The second region 19B is made of, for example,Al_(0.04)Ga_(0.96)N, and is doped with, for example, magnesium (Mg) as ap-type impurity. A thickness of the second region 19B is, for example,0.5 μm. However, an impurity concentration (dope amount) of the secondregion 19B becomes higher than an impurity concentration of the firstregion. A width (W1) of the first region 19A is the same as a width ofthe opening H1, and is, for example, 1.5 μm. Here, a configuration inwhich the first region 19A faces the opening H1, and the first regionand the opening are formed to have the same width as each other isexemplified; however, the width W1 of the first region 19A may be largerthan the width of the opening H1, or may be smaller than the width ofthe opening H1. A width (W2) of the second region 19B is, for example,1.0 μm. The p-type contact layer 20 is made of GaN, and is doped with,for example, magnesium (Mg) as the p-type impurity. A thickness of thep-type contact layer 20 is, for example, 0.01 μm.

An n-side electrode 11 is made of, for example, a laminated film of Ti,Al, Pt, and Au. The p-side electrode 21 is made of, for example, alaminated film of Ni, Pt, and Au, or a laminated film of Ni and Au. Insuch a semiconductor light-emitting element 1, a length of a resonatoris, for example, 0.8 mm, and width of a ridge stripe (a width W3 of thep-side electrode 21) is, for example, 3.0 μm.

Here, since the second semiconductor layer 19 is a p-type semiconductorlayer, a transport of charges (carriers) is performed by a hole. A holeis supplied from the p-side electrode 21 and is constricted in theopening H1 of the insulation film 18. At this time, an effective widthW4 of the p-side electrode 21 which contributes to a supply of a hole isnarrower than a width of a contact portion between the p-side electrode21 and the second semiconductor layer 19 when an actual width W3 of thep-side electrode 21 is sufficiently larger than the width W1 of theopening H1. Until the hole reaches near the opening H1 from the p-sideelectrode 21, a magnitude of a contact resistance with the p-sideelectrode 21 and a magnitude of a semiconductor bulk resistance aredetermined in accordance with the effective width (W4) of the p-sideelectrode 21.

The second region 19B at least partially has a higher impurityconcentration (herein, p-type impurity concentration) than the firstregion 19A. The impurity concentration of the second region 19B isdesirably set so as to obtain a sufficiently smaller resistance in thesecond region 19B than in the first region 19A. However, when theimpurity concentration of the second region 19B is too high, a crystalquality is impaired, and this rather causes a bulk resistance toincrease. Therefore, a ratio of the second region 19B to the firstregion 19A in impurity concentration is desirably from 2 to 20.

It is not necessary that an entire region of the second region 19B havea higher impurity concentration than the first region 19A. The secondregion 19B may include any portion which has a higher impurityconcentration than the first region 19A. In other words, a portion ofthe second region 19B may have a lower impurity concentration than thefirst region 19A. In addition, the impurity concentration of the secondregion 19B does not have to be the same in the second region 19B, andmay have a distribution. However, a wide range of the second region 19Bhas a higher concentration than the first region 19A, and thereby itbecomes easier to obtain an expansion effect of a current path.

The impurity concentration in the second region 19B is not particularlylimited, but is desirably 1.0×10¹⁸/cm³ to 1.0×10²⁰/cm³. This is becauseit is possible to realize a good bulk resistance of the p-typesemiconductor layer.

It is desirable that an electrical resistivity (specific resistance) inthe second region 19B is smaller than an electrical resistivity in thefirst region 19A. For example, it is desirable that the electricalresistivity of the second region 19B is set to be 1/20 to ½ of theelectrical resistivity of the first region 19A.

It is desirable that a width W2 of the second region 19B is set to be asize in which a hole can be sufficiently expanded in the secondsemiconductor layer 19. However, there is a limit on expansion of thehole, and even if the width W2 is increased to exceed the limit, a verylarge effect is not obtained. Rather, the increase in the width W2exceeding the limit causes an increase in manufacturing cost. Therefore,the width W2 is desirably, for example, 0.1 μm to 3.0 μm.

Manufacturing Method

FIG. 2 shows a flow of a manufacturing method of the semiconductorlight-emitting element 1 as described above. The semiconductorlight-emitting element 1 can be manufactured as follows. That is, first,a substrate 12 made of, for example, GaN, is prepared. A buffer layernot shown is grown on a surface of the substrate 12 under apredetermined growth temperature (for example, 1050° C.) by, forexample, a metal organic chemical vapor deposition (MOCVD) method.Thereafter, an n-type cladding layer 13 which is made of the materialdescribed above is grown on the substrate 12 (on the buffer layer) witha grown temperature maintained at, for example, 1050° C. by the MOCVDmethod (step S11). Subsequently, in the same manner, the n-type opticalguide layer 14, the active layer 15, the p-type electron barrier layer16, and the p-type cladding layer 17 are sequentially grown (steps S12to S15). Accordingly, the first semiconductor layer 10 is formed on thesubstrate 12.

When performing the MOCVD, for example, trimethyl gallium ((CH₃)₃Ga) isused as a source gas of gallium, for example, trimethyl aluminum((CH₃)₃Al) is used as a source gas of aluminum, and, for example,trimethyl indium ((CH₃)₃In) is used as a source gas of indium,respectively. In addition, ammonia (NH₃) is used a source gas ofnitrogen. Moreover, for example, monosilane (SiH₄) is used as a sourcegas of silicon, and, for example, bis(cyclopentadienyl) magnesium((C₅H₅)₂Mg) is used as a source gas of magnesium.

Subsequently, the insulation film 18 made of, for example, SiO2, isformed on the p-type cladding layer 17 (step S16). At this time, anopening H1 of a stripe shape is formed in the insulation film 18. Astripe direction (extending direction) of the opening H1 is set to beparallel to a (11-20) crystal surface.

Then, the second semiconductor layer 19 is formed (step S17 FIGS. 3A to3C). Specifically, as shown in FIGS. 3A and 3B, a growth temperature isset to, for example, 1000° C. by the MOCVD method to grow the p-typeAlGaN. Accordingly, the first region 19A is formed to face a regionexposed from the insulation film 18 on the first semiconductor layer 10,that is, the opening H1 of the insulation film 18 (step S171).Subsequently, as shown in FIG. 3C, the second region 19B is formed bysetting the growth temperature to, for example, 1150° C., and growingthe p-type AlGaN (step S172). At this time, the second region 19B isformed by a selective growth (lateral growth) so that crystal growthspeed in a (11-20) direction (X direction in the figure) is faster thanin a crystal orientation (0001) direction. As a condition of theselective growth, an appropriate condition may be set according to amaterial composition. However, for example, in a group III-V nitridesemiconductor as described in the embodiment, a growth temperature is aparameter contributing to the selective growth. Moreover, in a crystalgrowth process of the second region 19B, crystal growth is performed bychanging the first region 19A and a raw material ratio (compositionratio or impurity concentration (dope amount)). For example, a flow rateof a source gas of magnesium is increased more during a growth of thesecond region 19B than during a growth of the first region 19A. For thisreason, as described above, it is possible to increase impurityconcentration more in the second region 19B than in the first region19A.

Then, the grown temperature is set to, for example, 1050° C. by, forexample, the MOCVD method to grow the p-type contact layer 20 made ofthe material described above (step S18). Subsequently, the p-sideelectrode 21 is formed on the p-type contact layer 20 (step S19). On theother hand, the substrate 12 is, for example, wrapped and polished tohave a predetermined thickness (for example, about 100 μm), and then-side electrode 11 is formed on a rear surface of the substrate 12(step S20). At last, the substrate 12 is arranged to have apredetermined size, and reflection mirror films which are not shown areformed on a pair of facing resonator end surfaces. Accordingly, thesemiconductor light-emitting element 1 shown in FIG. 1 is completed.

Operation and Effect

In the semiconductor light-emitting element 1 of the embodiment, when apredetermined voltage is applied between the n-side electrode 11 and thep-side electrode 21, a constricted current in the opening H1 of theinsulation film 18 is injected into the active layer 15. Accordingly,light-emission due to recombination of electrons and holes occurs, thislight is reflected by the pair of reflector films which are not shown,and laser oscillation occurs at a wavelength at which a change in aphase during one reciprocation becomes an integer multiple of 2π to beemitted to the outside.

Here, FIGS. 4A and 4B show a configuration of a main portion and anoperation of the semiconductor light-emitting element (semiconductorlight-emitting element 100A) according to Comparative Example 1. In thesemiconductor light-emitting element 100A, a second semiconductor layer103 which configures a ridge portion is formed on a first semiconductorlayer 101 which includes an active layer 102, and a p-side electrode 104is formed on an upper surface of the second semiconductor layer 103. Thesecond semiconductor layer 103 is formed on the first semiconductorlayer 101 by a crystal growth, and is patterned to have a predeterminedstripe width (W101) by, for example, etching. In the semiconductorlight-emitting element 100A, as shown in FIG. 4B, it is possible toobtain a low threshold current density by current constriction.Moreover, it is possible to have a refractive index difference inside oroutside the ridge portion by embedding the second semiconductor layer103 (ridge portion) using an insulation material having a refractiveindex lower than a semiconductor, such that a so-called light transversemode is easily controlled. However, in such a structure, a contact areabetween the p-side electrode 21 and the second semiconductor layer 103is controlled to be the width W101 or less. Accordingly, an increase ina contact resistance with the p-side electrode 21 or a semiconductorbulk resistance is caused to increase a drive voltage.

FIGS. 5A and 5B show a configuration of a main portion and an operationof the semiconductor light-emitting element (semiconductorlight-emitting element 100B) according to Comparative Example 2. In thesemiconductor light-emitting element 100B, a second semiconductor layer106 (ridge portion) is formed on the first semiconductor layer 101including the active layer 102 through the insulation film 105 havingthe opening H100, and a p-side electrode 107 is formed on an uppersurface of the second semiconductor layer 106. The second semiconductorlayer 106 is formed by the crystal growth through the opening H100 ofthe insulation film 105, performs the crystal growth on the first region106A, and then performs a selective growth on the second region 106B ina transverse direction. However, an impurity concentration of the firstregion 106A is the same as an impurity concentration of the secondregion 106B in Comparative Example 2. Accordingly, a ridge can be formedwithout performing an etching. In addition, compared to ComparativeExample 1, it is possible to ensure a large contact area between thep-side electrode 107 and the second semiconductor layer 106, and toreduce a drive voltage.

Here, an effective ridge width or a current path cross-sectional area isdetermined by a current expansion from a current constriction portionnear the opening H1 to the p-side electrode 107 (in the secondsemiconductor layer 106). In the semiconductor light-emitting element100B of Comparative Example 2, a hole is transported while beingdiffused in the second semiconductor layer 106 (ridge portion), but haslow mobility. Thus, as shown in FIG. 5B, expansion of a current path d1is insufficient in the second semiconductor layer 106. In particular,since an activation energy of a p-type impurity is large in anitride-based semiconductor, it is difficult to obtain a sufficientcarrier density, and resistance of the p-type semiconductor is easilyincreased. Therefore, it is difficult to obtain an expansion effect ofthe current path due to a carrier diffusion (hole diffusion) in theridge. That is, since a hole which is multiple carriers in the p-typesemiconductor is difficult to expand in the p-type semiconductor with arelatively high resistance, an effective ridge width (W102 a) becomessignificantly smaller than an actual width (W102) of the p-sideelectrode 107. Therefore, it is not possible to sufficiently reduce adrive voltage.

FIG. 6A shows a configuration of a main portion of the semiconductorlight-emitting element (semiconductor light-emitting element 100C)according to Comparative Example 3-1. FIG. 6B shows a configuration of amain portion of the semiconductor light-emitting element (semiconductorlight-emitting element 100D) according to Comparative Example 3-2. In asemiconductor device 100C shown in FIG. 6A, a second semiconductor layer108 which configures a ridge portion is formed on the firstsemiconductor layer 101 including the active layer 102, and a p-sideelectrode 109 is formed on an upper surface of the second semiconductorlayer 108. In a semiconductor device 100D shown in FIG. 6B, a secondsemiconductor layer 108 a which configures the ridge portion is formedon the first semiconductor layer 101 including the active layer 102, anda p-side electrode 109 is formed on an upper surface of the secondsemiconductor layer 108 a. The second semiconductor layer 108 a of thesemiconductor light-emitting element 100D has an impurity concentrationhigher than the second semiconductor layer 108 of the semiconductorlight-emitting element 100C. As described in the semiconductorlight-emitting element 100D of FIG. 6B, it is possible to lower a drivevoltage by increasing an impurity concentration in the secondsemiconductor layer 108 a. However, when the impurity concentration isincreased, a light absorption characteristic is intensified. For thisreason, a light L102 is absorbed into the second semiconductor layer 108a, and it is difficult to obtain a sufficient light output.

In contrast, in the embodiment, the second semiconductor layer 19 whichconfigures a ridge portion includes the first region 19A facing theopening H1, and the second region 19B not facing the opening H1, and thesecond region 19B contains a portion which has a higher p-type impurityconcentration than the first region 19A. Accordingly, a hole carrierdensity in the second region 19B of the second semiconductor layer 19 ishigher than in the first region 19A, and an electrical resistivity ofthe second region 19B is lower than in the first region 19A. As aresult, a hole of the second semiconductor layer 19 is drawn into thesecond region 19B with a relatively low resistance, and is efficientlydiffused. Thus, a path (transport path) of carriers in the secondsemiconductor layer 19 is expanded, and a current path d is sufficientlyexpanded (FIG. 7). Accordingly, an effective ridge width Wr (aneffective width of the p-side electrode 21) becomes sufficiently largerthan an effective ridge width W102 a of Comparative Example 2.Therefore, contact resistance with the p-side electrode 21 of the secondsemiconductor layer 19 is reduced. In addition, the p-type semiconductorbulk resistance is reduced by expansion of the current path d.

In the embodiment as described above, it is possible to expand a currentpath in the second semiconductor layer 19 which has a relatively highresistance while maintaining a current constriction effect by theinsulation film 18 and light transverse mode controllability.Accordingly, it is possible to reduce a contact resistance with thep-side electrode 21 of the second semiconductor layer 19 and a bulkresistance. Therefore, it is possible to reduce a drive voltage whilemaintaining good properties.

EXAMPLE

A simulation as described below is performed on the semiconductorlight-emitting element 1 of the embodiment. As a simulator, a simulatorusing Maxwell's equations, Poisson's equations, rate equations, or thelike can be used. In addition, as a simulation model, a simulation modelwhich interposes a quantum well layer (In elemental ratio: 15%,thickness: 5 nm) made of GaInN using a barrier layer (In elementalratio: 4%) made of GaInN, and has an active layer 15 which sets thenumber of quantum well layers to be three layers is used. A lightemission wavelength of a nitride-based semiconductor laser including theactive layer 15 is about 450 nm. Furthermore, the active layer 15 isinterposed by the n-type cladding layer 13 and the p-type cladding layer17 to be driven as a semiconductor laser. In addition, a width of theopening H1 of the insulation film 18 made of SiO₂ is set to be 1.5 μm toform a p-type AlGaN cladding layer (Al composition ratio: 5%, p-typeimpurity concentration 3.0×10¹⁸/cm³, thickness: 500 nm) as the firstregion 19A of the second semiconductor layer 19. Moreover, a p-typeAlGaN cladding layer (Al composition ratio: 5%, p-type impurityconcentration: 3.0×10¹⁹/cm³, thickness: 500 nm, width W2: 1.0 μm) isformed as the second region 19B.

FIGS. 8 and 9 show a simulation result which is obtained by using asimulation model (referred to as model A) which corresponds to thesemiconductor light-emitting element 1 of the embodiment as describedabove. FIG. 8 shows a relationship of an element differential resistancewith respect to a current value, and FIG. 9 shows a relationship of acurrent density with respect to a distance from the center of a ridgeportion. This represents a current density distribution in a planeparallel to the substrate 12 in the second semiconductor layer 19.

In addition, FIG. 8 also shows a simulation result which is obtained byusing a simulation model (referred to as models B1 and B2) correspondingto each of Comparative Examples 1 and 2 described above. Moreover, FIG.9 shows a simulation result which is obtained by using a model B2corresponding to Comparative Example 2.

In the model B1 corresponding to Comparative Example 1, in aconfiguration shown in FIG. 4A, a p-type AlGaN cladding layer (Alcomposition: 5%, p-type impurity concentration: 3.0×10¹⁸/cm³, thickness:500 nm) is formed as the second semiconductor layer 103. Structuresother than the second semiconductor layer 103 are the same as in themodel A.

In the model B2 corresponding to Comparative Example 2, in aconfiguration shown in FIG. 5A, a p-type AlGaN cladding layer (Alcomposition: 5%, p-type impurity concentration: 3.0×10¹⁸/cm³, thickness:500 nm) is formed as the second semiconductor layer 106. An impurityconcentration of the first region 106A is the same as an impurityconcentration of the second region 106B to be (3.0×10¹⁸/cm³). Inaddition, a width W102 of the second semiconductor layer 106 is largerthan a width of the opening H100, and a width W2 of the second region106B is set to be 1.0 μm. Structures other than the second semiconductorlayer 106 are the same as in the model A.

As a result of simulation which is obtained by using these models A, B1,and B2, as shown in FIG. 8, a resistance value of model A having thesecond region 19B with a high impurity concentration becomes smallerthan in models B1 and B2. In addition, even if a resistance value in themodel B2 is smaller than in the model B1, its effect is smaller than themodel A. In addition, as shown in FIG. 9, current density distributionin the ridge portion is uniform in model A compared to model B2. Thisshows that a current path is expanded more extensively by the secondregion 19B which has a high impurity concentration in model A. Inaddition, it is considered that an effect that a resistance value shownin FIG. 8 is significantly reduced is obtained by the expansion of thecurrent path. In this manner, in the semiconductor light-emittingelement 1 of the embodiment, it is checked that an element differentialresistance can be significantly reduced compared to element structuresof Comparative Examples 1 and 2.

In addition, a relationship (V-I characteristics) of a voltage withrespect to a current in models A, B1, and B2 is shown in FIG. 10, and arelationship (L-I characteristics) of a light output with respect to acurrent in models A and B1 is shown in FIG. 11, respectively. In thismanner, the V-I characteristics and the L-I characteristics in model Aare improved compared to in models B1 and B2, and it is found that goodlaser characteristics are obtained.

Furthermore, a simulation result for a current density distribution ofmodel B2 corresponding to Comparative Example 2 is shown in FIGS. 12Aand 12B. FIG. 12B is an enlarged diagram of a vicinity of the insulationfilm 105 of FIG. 12A. A simulation result for a current densitydistribution of model A corresponding to the embodiment is shown inFIGS. 13A and 13B. FIG. 13B is an enlarged diagram of a vicinity of theinsulation film 18 of FIG. 13A. In these figures, a portion is shown soas to be closer to black as a current density becomes higher, and to becloser to white as the current density becomes lower. Compared to modelB2, it is found that the current density is increased in the vicinity ofa selective growth interface in model A. This shows that a carrierexpands more extensively in model A.

Hereinafter, modification examples of the semiconductor light-emittingelement of the embodiment will be described. The same numerals are givento the same configuration elements as in the embodiment described aboveto appropriately omit a description.

Modification Example 1

FIG. 14 shows a configuration of the semiconductor light-emittingelement (semiconductor light-emitting element 1A) according toModification Example 1. In the semiconductor light-emitting element 1 ofthe embodiment, a case in which the first semiconductor layer 10 formedon a layer lower than the insulation film 18 is made of the n-typecladding layer 13, the n-type optical guide layer 14, the active layer15, the p-type electron barrier layer 16, and the p-type cladding layer17 is exemplified, but a configuration of the first semiconductor layer10 is not limited thereto. As described in the modification example, theinsulation film 18 may be formed on a first semiconductor layer 10A madeof the n-type cladding layer 13, the n-type optical guide layer 14, andthe active layer 15. In this case, the p-type electron barrier layer 22is formed in the opening H1 of the insulation film 18, and the secondsemiconductor layer 19 including the first region 19A and the secondregion 19B is formed thereon. That is, a laminated structure of thefirst semiconductor layer 10A is not limited to the structure describedabove, but may include a p-type or an n-type (herein, n-type)semiconductor layer. The p-type electron barrier layer 22 is made of,for example, Al_(0.20)Ga_(0.80)N, and is doped with, for example,magnesium (Mg) as a p-type impurity. A thickness of the p-type electronbarrier layer 16 is, for example, 10 nm, and is formed at the same widthas, for example, the opening H1.

As described in the modification example, the insulation film 18 may beformed on the first semiconductor layer 10A made of the n-typesemiconductor layer (the n-type cladding layer 13, the n-type opticalguide layer 14, and the active layer 15). Even in this case, it ispossible to obtain the same effect as in the embodiment. In addition,for example, since a surface of the n-type semiconductor has a highflatness, the insulation film 18 having the opening H1 is formed easierthan in the embodiment.

Modification Example 2

FIG. 15 shows a configuration of the semiconductor light-emittingelement (semiconductor light-emitting element 1B) according toModification Example 2. In the modification example, the insulation filmhaving the opening H1 is configured to have a laminated film of a firstinsulation film 18 a and a second insulation film 18 b. In this manner,an insulation film of two or more layers may be laminated on the firstsemiconductor layer 10. A configuration material of the first insulationfilm 18 a and the second insulation film 18 b is not particularlylimited; however, for example, the first insulation film 18 a isconfigured from SiO₂ and the second insulation film 18 b is configuredfrom SiN. A thickness of the first insulation film 18 a and a thicknessof the second insulation film 18 b may be the same as or different fromeach other, but are, for example, 100 nm, respectively.

As described in the modification example, the laminated film made of thefirst insulation film 18 a and the second insulation film 18 b may beformed on the first semiconductor layer 10A, and even in this case, itis possible to obtain the same effect as in the embodiment describedabove. In addition, it is possible to further increase optical modecontrollability by selecting a combination of a refractive index and anabsorption coefficient of each of the first insulation film 18 a and thesecond insulation film 18 b.

Modification Example 3

FIG. 16 shows a configuration of the semiconductor light-emittingelement (semiconductor light-emitting element 1C) according toModification Example 3. In the modification example, a second region(second region 19B1) of the second semiconductor layer 19 has the sameconfiguration as the semiconductor light-emitting element 1 of theembodiment except for spatially having an impurity concentrationgradient (concentration distribution). In the second region 19B1, animpurity concentration is not limited to a case of being uniform, butmay have a concentration gradient in an X direction or a Y direction.That is, in the second region 19B1, growth conditions such as a rawmaterial ratio or temperature may be intentionally changed to be formed,or an unintentional concentration change may also occur. As describedabove, the second region 19B may even include a portion which has ahigher impurity concentration than the first region 19A, and the secondregion 19B may have an intentional or an unintentional concentrationgradient as described in the modification example. For example, thesecond region 19B1 may have a distribution in which the impurityconcentration is gradually increased from a side of the insulation film18 to a side of the p-side electrode 21.

As described in the modification example, even when the second region19B has the concentration gradient, it is possible to obtain the sameeffect as in the embodiment described above. In addition, it is possibleto perform a design to reduce a light absorption loss due to an impurityby adjusting the impurity concentration of the second region 19B1. Forexample, it is possible to suppress the light absorption loss due to animpurity by forming a distribution which allows the impurityconcentration to be gradually increased from the side of the insulationfilm 18 to the side of the p-side electrode 21 in the second region19B1.

Modification Example 4

FIG. 17 shows a configuration of the semiconductor light-emittingelement (semiconductor light-emitting element 1D) according toModification Example 4. In the modification example, an interfacebetween the first region (first region 19A2) and a second region (secondregion 19B2) is tapered in the second semiconductor layer 19.Specifically, a side surface of the first region 19A2 has a crystalorientation surface other than a (11-20) surface, for example, a (11-22)surface. In the modification example, the second region 19B2 also has aportion which has a higher impurity concentration than the first region19A2.

As described in the modification example, the side surface of the firstregion 19A2 may be a crystal orientation surface other than the (11-20)surface, and in this case, it is also possible to obtain the same effectas in the embodiment. In addition, it is possible to increase an averagevalue of the impurity concentration in the second semiconductor layer19, which is more advantageous for driving at a low voltage.

Modification Example 5

FIG. 18 shows a configuration of a main portion of the semiconductorlight-emitting element according to Modification Example 5. In themodification example, a second region (second region 19C) with higherimpurity concentration than the first region 19A is also formed on aside surface of the p-side electrode 21 in the second semiconductorlayer 19. In other words, the second region 19C is formed to cover aside surface and an upper surface of the first region 19A. A portion(third region 19C1) facing the p-side electrode 21 of the second region19C functions as a p-type contact layer. A thickness t of the thirdregion 19C1 is smaller than a width W2 of the second region 19C. Likethe second region 19B of the embodiment, the second region 19C is formedby selective growth after forming the first region 19A. During theselective growth, not only a crystal growth in the X direction, but alsoa crystal growth slightly in the Y direction proceeds due to theconditions. Since the third region 19C1 formed in a selective growthprocess of the second region 19C has a higher concentration than thefirst region 19A, the third region can function as a contact layer.However, since the p-type contact layer 20 of the embodiment is notadditionally formed in the modification example, it is desirable that animpurity concentration of the second region 19C is set to be1.0×10¹⁸/cm³ to 1.0×10²¹/cm³.

Modification Example 6

FIG. 19 shows a configuration of a main portion of the semiconductorlight-emitting element according to Modification Example 6. In theembodiment described above, a current path is expanded by increasing animpurity concentration of the second region 19B and the like in thesecond semiconductor layer 19; however, a configuration to expand thecurrent path is not limited thereto. For example, as described in themodification example, the current path may be configured so as to beexpanded by providing a current path control electrode (electrode 23)separately (electrically isolated) from the p-side electrode 21, andexpanding a transport path of carriers using the electrode 23. Theelectrode 23 is provided to correspond to, for example, the secondregion 19B. That is, the semiconductor light-emitting element of theembodiment of the disclosure may include any current path expansionunit. The current path expansion unit may be an impurity contained inthe first region 19A and the second region 19B at differentconcentrations described in the embodiments and the like, or may be aconfiguration including the electrode 23 as described in themodification example. In the modification example, it is possible tocause a negative fixed charge e on a surface of the insulation film 18by applying a predetermined electrode to the second region 19D throughthe electrode 23, and to draw a hole carrier to the second region 19Dside. In the modification example, impurity concentrations of the firstregion 19A and the second region 19D may be the same as or differentfrom each other.

As described above, description is provided with the embodiments andmodification examples; however, the disclosure is not limited to theseembodiments, and various modifications can be made. For example, aconfiguration of each layer and a lamination sequence of the n-typesemiconductor layer, the active layer, and the p-type semiconductorlayer described above are not particularly limited. In addition, it isnot necessary to include all of the layers described above, or otherlayers may be also included. For example, a p-type optical guide layermay be further included between the p-type cladding layer 17 and thep-type electron barrier layer 16. The semiconductor light-emittingelement of the disclosure may have a laminated structure having anactive layer between an n-type semiconductor layer and a p-typesemiconductor layer. In addition, the active layer may be an n type or ap type.

In addition, each configuration of the first semiconductor layer 10provided on a lower layer than the insulation film 18, and the secondsemiconductor layer 19 provided on a more upper layer than theinsulation film 18 is not limited to the configuration described above.For example, the first semiconductor layer 10 is obtained by laminatingthe n-type cladding layer 13, the n-type optical guide layer 14, theactive layer 15, and the p-type electron barrier layer 16, and theinsulation film 18 may be formed on the p-type electron barrier layer16.

Furthermore, in the embodiment and the like, it is exemplified that thep-side electrode 21 is formed almost over an entire upper surface of thesecond semiconductor layer 19, but the embodiment is not limited to theconfiguration. The p-side electrode 21 may be formed at a portion of theupper surface of the second semiconductor layer 19. The p-side electrode21 may be electrically connected to the second semiconductor layer 19.In the same manner, the n-side electrode 11 may be electricallyconnected to the first semiconductor layer 10, and does not necessarilyhave to be formed on a surface of the substrate 12.

Furthermore, a ridge portion of the semiconductor light-emitting elementdescribed in the embodiment and the like may be embedded by a materialsuch as other semiconductors, dielectrics, metals, and resins. Inaddition, an element upper surface may not necessarily be in a convexshape, but may be flat or in a concave shape.

Moreover, a crystal which configures the second semiconductor layer 19does not have to be a single crystal, but may be, for example, apolycrystal or an amorphous crystal.

Furthermore, a semiconductor which configures the second semiconductorlayer 19 is not limited to a nitride-based compound semiconductordescribed above, but may be another compound semiconductor. Moreover, inaddition to this, the semiconductor may be an oxide semiconductor suchas oxide indium gallium zinc (InGaZnO, IGZO) or zinc oxide (ZnO).Alternatively, the semiconductor may be, for example, amorphous orpolycrystalline silicon. The semiconductor device of the disclosure is,of course, applicable to a semiconductor laser or LED, but in additionto this, is also applicable to all types of semiconductor devices whichare obtained by laminating a semiconductor layer that exhibitsconductivity by impurity diffusion through an insulation film.

Effects described in the present embodiment and the like are no morethan an exemplification, and there may be effects other than the effectsdescribed herein, and other effects may be further included.

The present disclosure can also adopt the following configuration.

(1)

A semiconductor light-emitting element includes a laminated structurewhich has an active layer between a first conductivity-typesemiconductor layer and a second conductivity-type semiconductor layer,a first semiconductor layer which includes at least the firstconductivity-type semiconductor layer of the laminated structure, aninsulation film which is formed on the first semiconductor layer and hasan opening, and a second semiconductor layer which is formed on theinsulation film and includes at least the second conductivity-typesemiconductor layer of the laminated structure, in which the secondsemiconductor layer includes a first region facing the opening of theinsulation film and a second region not facing the opening, and thesecond region has a portion with a higher impurity concentration thanthe first region.

(2)

The semiconductor light-emitting element described in (1) furtherincludes a first electrode which is electrically connected to the firstsemiconductor layer of the laminated structure, and a second electrodewhich is electrically connected to the second semiconductor layer of thelaminated structure.

(3)

The semiconductor light-emitting element described in (2) in which thesecond electrode is formed on the second semiconductor layer and thesemiconductor light-emitting element further includes a secondconductivity-type contact layer between the second semiconductor layerand the second electrode.

(4)

The semiconductor light-emitting element described in (2) or (3), inwhich the second electrode is formed on the second semiconductor layer,and the second semiconductor layer includes a third region which has ahigher impurity concentration than the first region on a side surface onthe second electrode.

(5)

The semiconductor light-emitting element described in (4), in which athickness of the third region is smaller than a width of the secondregion.

(6)

The semiconductor light-emitting element described in any one of (2) to(5), in which the second electrode is formed on the second semiconductorlayer, and a contact area between the second semiconductor layer and thesecond electrode is larger than an opening area of the insulation film.

(7)

The semiconductor light-emitting element described in (6), in which thesecond region of the second semiconductor layer is formed to be adjacentto at least a portion of a side surface of the first region.

(8)

The semiconductor light-emitting element described in (7), in which thesecond region is formed, across which the first region is interposed.

(9)

The semiconductor light-emitting element described in any one of (1) to(8), in which a width of the second region is from 0.1 μm to 3.0 μm.

(10)

The semiconductor light-emitting element described in any one of (1) to(9), in which the second region includes a portion which has an impurityconcentration twice to 20 times higher than the first region.

(11)

The semiconductor light-emitting element described in any one of (1) to(10), in which the second region includes a portion which has animpurity concentration of 1.0×10¹⁸/cm³ to 1.0×10²⁰/cm³.

(12)

The semiconductor light-emitting element described in any one of (1) to(11), in which an electrical resistivity of the second region is smallerthan an electrical resistivity of the first region.

(13)

The semiconductor light-emitting element described in (12), in which theelectrical resistivity of the second region is 1/20 to ½ of theelectrical resistivity of the first region.

(14)

The semiconductor light-emitting element described in any one of (1) to(13), in which the second semiconductor layer is configured to have acompound semiconductor containing nitrogen (N) and at least one elementof gallium (Ga), aluminum (Al), indium (In), and boron (B).

(15)

A semiconductor light-emitting element includes a laminated structurewhich has an active layer between a first conductivity-typesemiconductor layer and a second conductivity-type semiconductor layer,a first semiconductor layer which includes at least the firstconductivity-type semiconductor layer of the laminated structure, aninsulation film which is formed on the first semiconductor layer and hasan opening, and a second semiconductor layer which is formed on theinsulation film and includes at least the second conductivity-typesemiconductor layer of the laminated structure, in which the secondsemiconductor layer includes a first region facing the opening of theinsulation film and a second region not facing the opening, and thesecond region has a smaller electrical resistivity than the firstregion.

(16)

The semiconductor light-emitting element described in (15), in which anelectrical resistivity of the second region is 1/20 to ½ of anelectrical resistivity of the first region.

(17)

A semiconductor light-emitting element includes a laminated structurewhich has an active layer between a first conductivity-typesemiconductor layer and a second conductivity-type semiconductor layer,a first semiconductor layer which includes at least the firstconductivity-type semiconductor layer of the laminated structure, aninsulation film which is formed on the first semiconductor layer and hasan opening, and a second semiconductor layer which is formed on theinsulation film and includes at least the second conductivity-typesemiconductor layer of the laminated structure, in which the secondsemiconductor layer includes a first region facing the opening of theinsulation film and a second region not facing the opening, and a pathof carriers in the second semiconductor layer is configured so as to beexpanded more than a width of the opening of the insulation film.

(18)

The semiconductor light-emitting element described in (17) furtherincludes a current path expansion unit which expands a path of thecarriers in the second semiconductor layer.

(19)

The semiconductor light-emitting element described in (18), in which thecurrent path expansion unit is one of a plurality of electrodes eachprovided to correspond to one of the first region and the second region,and impurities contained in the first region and the second region atdifferent concentrations.

(20)

A method of manufacturing a semiconductor light-emitting elementincludes forming a first semiconductor layer which includes at least afirst conductivity-type semiconductor layer of a laminated structurethat has an active layer between the first conductivity-typesemiconductor layer and a second conductivity-type semiconductor layer,forming an insulation film which has an opening on the firstsemiconductor layer, and forming a second semiconductor layer whichincludes at least the second conductivity-type semiconductor layer ofthe laminated structure on the insulation film, in which, in the formingof the second semiconductor layer, a first region facing an opening ofthe insulation film is formed, and a second region not facing theopening is formed by selective growth after forming the first region.

(21)

The method of manufacturing a semiconductor light-emitting elementdescribed in (20), in which the second region includes a portion whichhas a higher impurity concentration than the first region.

(22)

The method of manufacturing a semiconductor light-emitting elementdescribed in (20) or (21), in which a raw material ratio when formingthe first region and a raw material ratio when forming the second regionare different from each other in the forming of the second semiconductorlayer.

(23)

The method of manufacturing a semiconductor light-emitting elementdescribed in (22), in which, in the forming of the second semiconductorlayer, each of the first region and the second region grows while asource gas including an impurity thereto is supplied, and a supplyamount of the source gas when forming the second region is set to bemore than when forming the first region.

(24)

The method of manufacturing a semiconductor light-emitting elementdescribed in (20), in which, in the forming of the second semiconductorlayer, the first region and the second region are formed by differentgrowth conditions.

(25)

The method of manufacturing a semiconductor light-emitting elementdescribed in (24), in which the first region and the second region areformed by different growth temperatures.

(26)

A semiconductor device includes a first semiconductor layer, aninsulation film which is formed on the first semiconductor layer and hasan opening, and a second semiconductor layer which is formed on theinsulation film, in which the second semiconductor layer includes afirst region facing the opening of the insulation film, and a secondregion not facing the opening, and the second region has a portion witha higher impurity concentration than the first region or has a smallerelectrical resistivity than the first region.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A method of manufacturing a semiconductorlight-emitting element comprising: forming a first semiconductor layerwhich includes at least a first conductivity-type semiconductor layer ofa laminated structure that has an active layer between the firstconductivity-type semiconductor layer and a second conductivity-typesemiconductor layer; forming an insulation film which has an opening onthe first semiconductor layer; and forming a second semiconductor layerwhich includes at least the second conductivity-type semiconductor layerof the laminated structure on the insulation film, wherein, in theforming of the second semiconductor layer, a first region facing anopening of the insulation film is formed, and a second region not facingthe opening is formed by selective growth after forming the firstregion.
 2. The method of manufacturing a semiconductor light-emittingelement according to claim 1, wherein the second region includes aportion which has a higher impurity concentration than the first region.3. The method of manufacturing a semiconductor light-emitting elementaccording to claim 1, wherein a raw material ratio when forming thefirst region and a raw material ratio when forming the second region aredifferent from each other in the forming of the second semiconductorlayer.
 4. The method of manufacturing a semiconductor light-emittingelement according to claim 3, wherein, in the forming of the secondsemiconductor layer, each of the first region and the second regiongrows while a source gas including an impurity thereto is supplied, anda supply amount of the source gas when forming the second region is setto be more than when forming the first region.
 5. The method ofmanufacturing a semiconductor light-emitting element according to claim1, wherein, in the forming of the second semiconductor layer, the firstregion and the second region are formed by different growth conditions.6. The method of manufacturing a semiconductor light-emitting elementaccording to claim 5, wherein the first region and the second region areformed by different growth temperatures.
 7. The method of manufacturinga semiconductor light-emitting element according to claim 1, wherein thefirst semiconductor layer is a III-V nitride semiconductor.
 8. Themethod of manufacturing a semiconductor light-emitting element accordingto claim 1, wherein the second semiconductor layer is a III-V nitridesemiconductor.